This invention relates to short fiber or particle textured articles.
Materials textured with short fibers or texture particles on their surfaces are used as, for example, dental hygiene articles (e.g., toothbrushes, dental floss, interdental brushes) and abrasives (e.g., manicure or pedicure products, cleaning products). Currently, the short fibers or texture particles are ordinarily attached to a surface using an adhesive.
The invention is based on the discovery that textured surfaces (e.g., for use as dental floss, or toothbrush bristles) can be manufactured without using adhesives to secure the short fibers or texture particles to the base material, or substrate. The textured materials are formed by thermally or chemically softening a preformed substrate (e.g., sheets, fibers, or filaments made of nylon, TEFLON(copyright) fibers, KEVLAR(copyright) fibers, cotton, polyester, polyethylene, or other plastic), then an electrostatic applicator is used to apply short fibers or texture particles to the softened substrate. Alternatively, the short fibers or texture particles can be applied during the formation of the substrate (e.g., in an extrusion, melt-blowing, die casting, weaving, or drawing process).
In general, the invention features a methods for manufacturing a textured article. The article can be, for example, a dental hygiene product (e.g., an oral brush bristle, a dental floss filament). The method includes the steps of contacting texture particles (or an end of short fibers having two ends) and a surface of a substrate under conditions in which a part of either the texture particles (or short fibers), the substrate, or both are softened (e.g., by treatment with a solvent or by heating); and hardening the softened part to produce the textured article.
The contacting step in the above methods can occur, for examples after extrusion of the substrate but prior to the cooling of the substrate in a heat extrusion process that includes an extrusion step and a cooling step.
The methods that include the use of short fibers can also include the step of supplying an electromagnetic field, which can cause the short fibers to align at a substantially fixed angle relative to the surface of the substrate. The short fibers can, for example, be coated with an electrically conductive material (e.g., tannic acid and starch).
The articles made by the methods described above are also contemplated as an aspect of the invention, as are toothbrushes and interdental brushes including bristles made by the above methods and dental flosses including filaments made by the above methods. Such articles can also include an active ingredient, possibly mixed with a water soluble material such as starch, pectin, or cellulose.
A different embodiment of the invention features another method for manufacturing a textured article. The method includes the steps of extruding a bilayer substrate, in which an outer layer includes short fibers; and providing an electromagnetic field prior to cooling the substrate, causing the short fibers to align at a substantially fixed angle relative to the surface of the substrate, to produce the textured article.
The substrate can be, for example, a coaxial filament having a sheath/core arrangement, where the first layer is the sheath, and the second layer is the core.
Still another embodiment of the invention also features a method for manufacturing a textured article. This method includes the steps of spraying a suspension that includes short fibers onto the surface of a substrate; and then providing an electromagnetic field, causing the short fibers to align at a substantially fixed angle relative to the surface of the substrate, to produce the textured article.
The suspension can include, for example, a polymer dissolved in a solvent, in which case the method also includes the step of removing the solvent to cause the short fibers to become fixed in the polymer at the fixed angle.
Alternatively, the suspension can include a molten polymer; and the method further comprises cooling the polymer to cause the short fibers to become fixed in the polymer at said angle.
Still another embodiment of the invention features an oral brush (e.g., a toothbrush or interdental brush) including a bristle that has short fibers attached without requiring an adhesive.
Yet another embodiment of the invention features dental floss including a filament that has short fibers attached without requiring an adhesive.
The short fibers can be attached to the bristle of the oral brush, for example, or the filament of the dental floss, by thermally or chemically softening an end of the short fibers, then contacting the bristle or filament with the softened end of the short fibers. Alternatively, the short fibers can be attached to the bristle or filament by thermally or chemically softening a surface of the bristle or filament, then contacting the softened bristle or filament with the short fibers. In another alternative, the short fibers can be attached to the bristle or filament by extruding a coaxial bristle or filament, where the outside layer contains short fibers having a net dipole, and then providing an electromagnetic field prior to cooling, causing the short fibers to align at a substantially fixed angle relative to the surface of the bristle or filament. Optionally, the short fibers can include an active ingredient.
Advantages of the new articles and methods include improved mechanical properties, enhanced biocompatibility, increased control over the physical configuration of the products, and the potential for use as a reservoir for release of therapeutics in a free or controlled release (i.e., particle) form.
Short fibers or particles are attached to the substrate by a melting or dissolving process; thus, the use of toxic adhesives can be avoided.
Another advantage follows-from avoiding the use of adhesives: in general, the new methods result in a stronger attachment of the short fibers to a substrate, relative to adhesive-based methods; in some cases, the attachment is permanent. Thus, the new methods can yield products having greater mechanical integrity.
Because electrostatically charged particles or short fibers can be aligned by an electromagnetic field, the angle at which such fibers are fixed to the substrate can be precisely controlled.
Toothbrush filaments textured with short fibers or particles can penetrate deeper into interdental regions during brushing; such filaments can be constructed with smaller diameter than traditional toothbrush filaments, yet can nonetheless exhibit excellent mechanical integrity and bend recovery.
Textured dental floss can also provide a larger surface area for cleaning while flossing.
Other features and advantages of the new articles and methods will be apparent from the following detailed description, and from the claims.